Sewing machines



Sept. 16, 1958 Filed March 25. 1953 A. H. ERIKSSON SEWING MACHINES 2Sheets-Sheet 1 Sept. 16,.1958 A. H. ERIKSSON 2,851,978

SEWING MACHINES Filed March 25. 1953 u 2 Sheets-Sheet 2 ATTORNEY UnitedStates Patent SEWING MACHINES Allan Herman Eriksson', Huskvarna',Sweden, assignor to Husqvarna Vapenfabriks Aktiebolag, Huskvarna,Sweden, a corporation of Sweden Application March 25, 1953, Serial No.344,560 Claims priority, application Sweden March 26, 1952 9 Claims.(Cl. 112-232) This invention relates to stitch forming mechanisms forsewing machines, and more particularly to lock stitch formmgmechanisms-of the type comprising a-reciprocating needle bar and arotary shuttle, housing a nonrotating spool case and having a loop takerhook at its circumfer-.

in the risk of jamming threads is excluded and the friction is reducedto a minimum. A further object of the invention is to provide a novelshuttle mechanism without raceway wherein the case with a spool thereinmay readily be taken out.

With the above and other objects in view, as will hereinafter appear,the invention comprises the novel com binations and arrangements-ofparts hereinafter set forth and illustrated in the accompanyingdrawings, and the advantages attained thereby will be readily understoodby those skilled in the art.

The invention will be more particularly described in the following withreference to the annexeddrawing illustrating an application of theinventionto a lock-stitch sewing machine with a cantilevered fabricsupportingarm.

Fig. l is a schematic end view of the machine, partly in cross-sectionthrough the supporting arm. Fig.- 2 is a front view of the stitchforming mechanism disposed in the free end of the supporting arm. Figs.3-5show the shuttle in three different projections. Figs. 6 and 7 showthe shuttle driving member in front and'side view, respectively. Fig. 8is a plan view of its retaining member and Fig. 9 a side view of thespoolcase. Figs. 10-12 show the shuttle, its driving member and thespool case in three different working positions. Figure 13 is an axialvertical section through the shuttle and thedriver when about in theposition corresponding to the top most position of the needle which isoccupied somewhat after the position shown in Figure 12, the sectionbeing taken between the hook and the lug, and Figure 14 is a sectionaldetail illustrating the latching of the spool holder or case to theshuttle.

The frame of the machine shown comprises a standard 1, a cantileveredfabric supporting arm 2 and a needle head 3 disposed above the arm 2and'carryihg a vertically movable needle bar 4 with a needle 5, a threadtakeup lever 6 and other known means (not shown) for conducting theupper thread from a thread reelt'o the fabric. The supporting arm 2houses means for feeding the fabric in the transverse direction of thearm, towardsthe left in Fig. l which means may be of known constructionand are therefore not shown, as well aslower stitch'forming meansavailable through an opening 8 in the supporting arm which is providedwith a lid 7 for said opening and with a stitch plate 9.

The said stitch forming means comprise a substantially cup-shapedshuttle 20, Figs. 3-5, having a central pivot 21 for a spool case,apreferably substantially circular-circumferential-flange 22 wherein aloop taker hook 23 is formed, and an annular, axially acting cam 25 foroperating the under thread, said cam being provided with a peripheralslot 24 for the needle. The shuttle 20 is supported at its circumferencebetween a substantially concave member 30 for carrying and driving theshuttle, and a stationary retaining member supporting the shuttle 20axially, preferably a substantially ring-shaped cover plate providedwith a recess '41 for the needle on its side facing the shuttle-20, Pig.8. The driving member 30 shown is provided on its circumference withaxially as Well as radially extending bearing surfaces 31 and 32,respectively, for the shuttle flange 22, and with a seat recess 33 toreceive a lug 26 on the shuttle 2t) laterally of the flange 22 fortransmitting movement from member 30 to shuttle 20.

In the embodiment shown the shuttle 20 is adapted to rotate about ahorizontal axis parallel to the fabric feeding direction, the drivingmember 39 being mounted on a transverse shaft 10 journaled in thesupporting arm 2 and, preferably by means of a bevel gear 11, connectedto a drive shaft 12 extending longitudinally in the supporting arm 2.The movement of this shaft 12 is preferably such that the shuttle 29rotates with constant (uniform) speed in the clockwise direction in Fig.2, making two revolutions for each up and down movement of the needle.The movement transmitting lug 26 should belocatedconsiderably less than90 in front of the hook 23. The retainer 40 is detachably secured bymeans of screws-13 to a member 14 rigidly mounted in the supporting arm2. The shuttle 2% should have an axial play between the members 30and'40 corresponding to the maximum thread thickness to be used, and mayalso have some play perpendicularly thereto. The shuttle bearing partsof the driving member 30 and/ or the retainer 40 arepreferably of a moresound-deadening material than solid metal, such as porous sinter metalor, better, a nonmetallic material, such as a plastic. The drivingmember 30 may wholly consist of a plastic, such as nylon ortextilearmoured Bakelite, and the retainer it) may be provided with alining 42 thereof. Alternatively, the bearing part of the shuttle 24 theflange 22 may be of such material.

The spool case should be substantially smoothon its outer end surface tobe passed by the upper-thread. The spool case shown in Fig. 9, for aconventional under-thread spool not shown, has a cylindrical mantle 50and a bottom part 51 remaining between two diametrically oppositeopenings and shaped to form afinger grip, said part 51 carrying acentral, tubular'shank '52 fitting inthe spool and on the pivot 21 ofthe shuttle, said pivot 21 having a peripheral groove 27 on its freeend. A locking member 54, 55' mounted inside :the bottom part 51 andpreferably swingable. on a pivot 53, is adapted to engage into thegroove 27 with .the part 54 under the pressure of a spring 56, Fig. 2,whereas the other part 55 is adapted to be manually operated whengripping the bottom part 51, whereby the spool case can be released fromthe shuttle 20 and the part 55 will engage the adjacent edgeof the spoolwith its inturned free end, particularly visible in Fig. 9, therebyretaining the spool in the spool case. The mantle 50 of the case isprovided at its top with anopening 57 for the needle and upon one sidewith a thread tensioning leaf: spring 58 covering a through-hole for theunder thread;'this latter feature being well-known in the art andtherefore not particularly shown in the drawing. The spool case also hasa finger 59 which is formed on the locking member 54, 55 and projectthrough the opening 57 but which, preferably, is rigidly mounted on thecase, said finger engaging, with some play, into a recess 43 formed inthe upper part of the retainer 40, Fig. 2, the edges of the recess 43adjacent the shuttle 20 being preferably chamfered in known manner inorder to facilitate the passage of the upper thread. If desired, thisrecessed upper part of the retainer 40 may be formed integral with thelining 42.

The operation of the mechanism described is illustrated by Figs. -12,wherein a denotes the upper thread and b the under thread which isassumed not yet to have been fastened in the fabric. Moving downwardsthe needle enters the slot 24 in the shuttle, the flange 22 of which ispreferably somewhat charnfered at the location 28, Fig. 3, passed by thepoint of the descending needle. Extending into said slot 24 the needleis capable of keeping the shuttle in an axial position wherein the book23 will not strike the needle, a part 22a extending in front of the hook23 being adapted to engage the side of the rising needle when the hook23 is about to pass the same. The preceding part of flange 22 may beprovided with a slight axial depression 28a in order to eliminate orreduce the contact between the flange 22 and the very eye-part of theneedle. In Fig. 10 the hook 23 has just passed the needle which hasmoved upwardly, forming a thread loop for which ample space may beprovided by an axial depression 34 in the circumference of the driver30, Fig. 6, and which is taken by the hook 23. By further rotation ofthe shuttle the loop is widened and thrown around the spool case, theloop passing freely past the outside of the bottom of the spool case andthe shuttle 20. In order to facilitate the thread running on the shuttlebottom, the driver 30 is provided with an axial depression 35 laying theflange 22 bare at a part of its circumference to be passed by the upperthread at the instant in question. While the shuttle 20 is moving fromthe position in Fig. 11 to the position in Fig. 12, the upper thread ais tightened by the take-up lever 6, the thread passing easily the lug26 and leaving the shuttle 20 while embracing the under thread b. Whenthe latter has been fastened in the fabric, it is pulled forward by thecam which for this purpose is of varying height axially. When beingtightened, the upper thread a passes between the under thread b and theedge of the hole in the stitch plate. In order to facilitate thispassage, the cam 25 is provided with a depression 29 at the part of itscircumference engaging the thread during said passage, whereby thetension of the under thread b will be reduced for the moment inquestion.

The three main cooperating elements are the shuttle 20, the drivingmember 30 and the fixed retainer or annular cover plate 40. The shuttle20 includes a concave or dished body which is circumscribed by theflange 22 and the driving member is of concave or dished form forreceiving the dished body of the shuttle. The said flange is supportedin the seat provided by the bearing surfaces 31 and 32 and the retainingand driving members are so spaced that the intervening shuttle haslimited axial movement for passage of the inner limb of a needle threadloop between the driving member and shuttle. Furthermore, the recess 33in the driving member is slightly wider than the shuttle lug 26 forpassage of said thread loop limb upon slight relative circumferentialmovement of the driving member and shuttle. The outer limb of saidneedle thread loop passes over the bobbin casing or mantle 50 andbetween the finger 59 and its receiving recess 43 in which the fingerhas slight circumferential movement. p

The stitch forming mechanism described is particularly suitable fordomestic sewing machines and may be used to advantage also in zigzagsewing machines wherein the needle bar is in known manner movable in aplane perpendicular to the fabric feeding direction. In said mechanismthe upper thread does not have to lift some part of the mechanism. Therisk of jamming threads is excluded, and the friction is reduced to aminimum. At the exchange of spools the spool case with a spool thereinmay readily be taken out through the opening in the ring-shaped retainer40 which, consequently, does not have to be removed for changing spools.

Also various other embodiments are possible within the scope of theinvention. The shuttle may, for instance, also be mounted for rotationin a vertical plane through the fabric feeding direction.

What I claim is:

1. A stitch forming mechanism, comprising in combination, a rotaryshuttle including a circumferential flange provided with a loop takingbook, a shuttle driving member adapted for continuous rotary movementand provided circumferentially thereof with axial and radial bearingsurfaces defining a seat for said shuttle flange, said shuttle and saiddriving member being provided with cooperating rotation transmittingmeans, and a stationary member disposed adjacent said flange inopposition to said driving member for confining said shuttle forrotation with said driving member with limited axial play between thesaid radial bearing surface and said stationary member.

2. In a sewing machine, the combination of a vertically reciprocatingneedle bar, a rotary shuttle having a circumferential flange providedwith a loop taking book, a shuttle driving member supported for rotationin a plane parallel to said needle bar and provided circumferentiallythereof with axial and radial bearing surfaces defining a seat for saidflange, said shuttle and said driving member being provided withcooperating rotation transmitting means, and a stationary memberdisposed adjacent said flange on the side thereof opposite said drivingmember and being spaced from said radial bearing surface a distanceslightly greater than the thickness of said flange for bodily axialmovement of said shuttle in said driving member for passage of the innerlimb of a needle thread loop therebetween.

3. In a lock stitch sewing machine, a shuttle comprising a dished bodyhaving a peripheral flange encircling same for the major circumferencethereof, a bobbin case pivot stud projecting from the base of said bodyin the axis of rotation of the shuttle, one end of said flange beingprovided with a loop taking hook, a rotation transmitting lug on theopposite end of said flange, a driving member having a recess in whichsaid lug is loosely received and said flange being provided with aperipheral depression adjacent said rotation transmitting lug.

4. A stitch forming mechanism, comprising in combination with a verticalreciprocating needle, a dished shuttle driving member having the basethereof secured to a rotary shaft disposed at right angles to saidneedle, a rigidly supported annular cover plate disposed in spacedparallel relation to said driving member, and a dished shuttle disposedbetween said driving member and said cover plate, said driving memberhaving an annular seat and a recess in the annular wall thereof, saidshuttle having an annular flange with one side thereof engageable withsaid seat, and having a lug loosely supported in said recess for passageof the inner limb of a needle thread loop past same, and said coverplate being disposed in such spaced relation to said driving member forslight axial movement of said shuttle for passage of said thread looplimb between the base thereof and the base of said driving member.

5. A stitch forming mechanism according to claim 1 in which saidrotation transmitting means comprises a rotation transmitting lugprojecting from one of said shuttle and driving member and the other ofsaid shuttle and driving member having a recess loosely receiving saidlug and wherein said shuttle is of metallic material and said drivingmember is of non-metallic material having characteristics for deadeningsound occasioned by axial impact between the shuttle and shuttle drivingmember and rotary impact between the lug and the wall of said recess.

6. A stitch forming mechanism according to claim 1 wherein said shuttleis adapted to support a bobbin case having a rotation restrainingfinger, and wherein said stationary member is provided with a recessloosely receiving said finger, and said stationary member being ofnon-metallic material for sound deadening of impact between said fingerand the wall of said recess.

7. A stitch forming mechanism'according to claim 1, wherein surfaces ofcontact between said shuttle and said members are formed by parts of amaterial having characteristics for deadening sound occasioned by axialimpact between the shuttle and said members.

3. A stitch forming mechanism according to claim 1, wherein the shuttlehas a guide part extending from the base of said hook in the directionof movement thereof and adapted to engage one side of the needle whenthe hook is about to pass the same, so as to keep the hook from strikingthe needle due to said axial play of the shuttle.

9. A sewing machine according to claim 2, wherein said rotationtransmitting means comprises a rotation transmitting lug projecting fromsaid flange, said driving member having a recess loosely receiving saidrotation transmitting lug, said recess being disposed in advance of saidloop taking hook at an angle less than and wherein the driver has auniform rotary movement and is adapted to make two revolutions at eachreciprocating movement of the needle bar.

References Cited in the file of this patent UNITED STATES PATENTS

